Hierarchical routing and network summarization are approaches realized in order to solve scalability issues for routing in a multi-domain scenario. The global topology of a multi-domain network comprising a huge number of nodes can cause scalability issues.
A hierarchical path calculation element (PCE) for multi-domain scenario is described in IETF RFC-4655. In this model there are two levels of path computation. The high level is named Parent PCE and it is responsible for end-to-end (E2E) path computation. It works on a virtual topology composed by a set of summarized domains. The low level is composed by a child PCE that has the complete vision of a single domain. Each child PCE provides the summarized topology to the Parent PCE that composes the E2E virtual topology of all domains.
Summarization, in a multi-domain context, is a way to depict a network physical resources set with a logical network, in order to reduce the amount of topology information to be distributed through the physical network. This decreases routing computation time and preserves confidentiality of each domain.
It is not known to provide Traffic Engineering (TE) paths that can efficiently adapt resources without any knowledge of the end-to-end traffic and network status.